Solar Resource:
● What is the solar energy production
potential for the location?
● How does the specific site effect the
installation - production and installation
wise?
● Customer assessment: What does the
customer expect and want?
Solar Site Assessment
objectives:

● Solar Resource:
○ Latitude
○ solar sun path charts
○ Altitude and Azimuth - sun and array positioning
● Site Specific Practical:
○ Shading - Solar Pathfinder or Suneye
○ Mounting methods and locations
○ Component locations and wire runs
○ Electrical service - new construction or retrofit
○ Roof or soil conditions
Solar Resource and Site
Analysis

Solar resource
Does the sun shine?
● What does data say for location?
○ Latitude, solar sun path charts
■ Azimuth - position relative to South
■ Altitude - how high in the sky
● What is the weather/air like?
○ wind patterns
○ rainfall
○ pollution

Latitude has an
incredible influence on
the available solar
resource.

Location - Latitude
Sun strike, wind/weather patterns, elevation

Peak Sun Hour (PSH) Data
Resource Tables

Austin, Texas:
84 days rainfall average
229 sunny days/year
30º Latitude
489 ft. Altitude
Frankfurt, Germany:
1,586 hours sun/year
51ºN Latitude
364 Ft. Altitude
Latitude
Germany:
2011: 69,684
2012: 102,024
USA:
2011: 4,383
2012: 7,665
MWp Peak Power Capacity (installed, not resource)

Kenya:
13 - 71 days rainfall
3,579 Hours/year
0º Latitude
6000 Ft. Altitude
Sydney:
155 days rainfall
235 sunny days/year
39ºS Latitude
128 Ft. Altitude
Kenya:
Australia:
2011: 1,298
2012: 2,291
South Africa:
2011: 41
2012: NA
MWp Peak Power Capacity (installed, not resource)
Latitude

Location and Latitude
Sun strike, wind/weather patterns, elevation

Berlin, Germany:
1,586 hours sun/year
51ºN Latitude
114 Ft. Altitude
Germany:
2011: 69,684
2012: 102,024

Austin, Texas:
229 Sunny Days/year
30º Latitude
489 ft. Altitude
USA:
2011: 4,383
2012: 7,665

Kenya:
13 - 71 days rainfall
3,579 Hours/year (325 days)
0º Latitude
6000 Ft. Altitude
South Africa: 2011: 41
2012: NA

Sydney:
155 days rainfall
235 sunny days/year
39ºS Latitude
128 Ft. Altitude
Australia:
2011: 1,298
2012: 2,291

Solar and Wind Energy Resource Assessment:
http://maps.nrel.gov/swera
Other examples:
Indonesia is practically at the equator, yet the
solar resource is fairly poor because it rains
there SOO much.

Other examples:
Hawaii- 10 climate zones in 4000 square miles

Azimuth and altitude of the
sun and array dramatically
affect the ability to maximize
a locations natural solar
resource.
graphic from: astronomy21st.blogspot.com
** Note: mostly
using Northern
hemisphere for
examples.

http://www.solarfeeds.com/
The solar window is defined by the solar altitude and solar
azimuth.

A sun path chart is a graphic representation of the solar
window that gives precise data regarding the exact
location of the sun at all times of the year.

9AM - 3PM
68º
How do you read a sun path chart?

68º - Solar altitude angle on June 21
summer solstice

22º - Solar altitude angle on December 21st
winter solstice

Yellow Sun = Sunrise in Winter
Red Sun = Sunset in Summer
South = 0º
+/- 180º
90º- 90º
W
E
N
W
E
Solar
Window

Solar angles
South = 0º
+/- 180º
90º- 90º
W
E
N
W
E
?
?

Solar angles
South = 0º
+/- 180º
90º- 90º
W
E
N
W
E
Solar Azimuth
Angle
Solar altitude
angle

S
NW
E
40º E solar azimuth
9AM, Dec 21
40º

S
N
W E
-34º W
1PM, June 2134º

S
0º
E
90º
W
-90º
N
-/+ 180º
What is the azimuth angle of each array?
Which one will produce the most in the morning?
Which one will produce the most in the evening?
?
?
Array azimuth

S
0º
E
90º
W
-90º
N
-/+ 180º
What is the azimuth angle of each array?
(At what angle does it face in reference to
South?)
40ºW
or -40
50ºE

S
0º
E
W
N
-/+ 180º
40ºW
or -40
50ºE

S
0º
E
W
N
-/+ 180º
40ºW
or -40
50ºE
Will do best in the AM, when Sun is in the Eastern sky
Will do best in the PM, when Sun is in the Western sky
Will most often do best of all

In an environment that experiences rain in
the morning fairly regularly, but that clears
up around noon with clear skies on into the
evening, what would be the ideal direction
(azimuth) relative to South for the array to
face?

In an environment that experiences rain in
the morning fairly regularly, but that clears
up around noon with clear skies on into the
evening, what would be the ideal direction
(azimuth) relative to South for the array to
face?
The sun rises in the E, and sets in the W.
The array should face towards an azimuth
that is slightly west of south.
This will allow for optimization of afternoon
sun, after the skies clear.

S
0º
E
90º
W
-90º
N
-/+ 180º
A home has a roof that is shade free with an
azimuth of 103º. Will this work for a solar array?

S
0º
E
90º
W
-90º
Would this work?
N
-/+ 180º

S
0º
E
90º
W
-90º
It wouldn't be good.
N
-/+ 180º

When does it make sense to have
an array face North?
For example, on the back side fo this house?

When does it make sense to have
an array face North?
In the Northern Hemisphere-
NEVER.
In the southern Hemisphere-
ALWAYS.

http://131.91.162.18/nasa/module-3/why-does-temperature-vary/angle-of-the-sun
Direct vs. Indirect Solar radiation
wider area and more atmosphere to pass through

http://www.astronomy.org/programs/seasons/

The angle of incidence is essentially the angle that
defines how far you are away from a direct line from
the sun.
The larger the incidence angle, the less solar
radiation/photons will strike the surface.
solar altitude angle
relative to roof

http://naturalfrequency.com/wiki/insolation
Altitude angle + incidence angle = 90º

Incidence angle: It is best to face the
solar rays for most direct absorption
of photons.
Hence- arrays facing South, (Northern
Hemisphere), TILTED at latitude.

blog.civitasenergy.com
Module should be tilted so that the Incidence angle is at 90º
to the sun's rays (set at tilt angle equal to latitude).
If possible:
Winter- tilt up 15º (Latitude + 15) because of lower solar
altitude angle
Summer- tilt back 15º (Latitude - 15) because of greater
solar altitude angle

Incidence angle: It is best to face the solar rays
for most direct absorption of photons.
Hence- arrays facing South, (Northern
Hemisphere), TILTED at latitude.

Site specific details
Will it work on my house?
"It depends."

Site specific details
○ Shading
○ Mounting methods and
locations
○ Roof or soil conditions
○ Component locations and
wire runs
○ Electrical service - new
construction or retrofit

http://wiki.naturalfrequency.com/wiki/Shadow_Angles
Solar
Azimuth
effects
on
Shading

Shading
Consider shadows cast by objects such as
trees, wires, ducts, antennae, etc. as well as
seasonal lighting concerns.

SolarPro Article:
Q & A Calculating Inter-Row
spacing
#SolarMOOC Lecture:
http://solpowerpeople.com/inter-
row-shading/

Solar Pathfinder
solarpathfinder.com

Solmetric SunEye:
More advanced
shade analysis
GPS built in
software that
allows a shading
analysis to be
created to shared

There are many smartphone
apps for shading analysis as
well:
Sun Surveyor (android)
SunSeeker (iPhone)
(each app is about about $2 - $5)
SolarPro article:
iPhone Apps for Solar Geeks

Magnetic Declination
Eastern Declination Western declination

Magnetic Declination
180 - (MD) = True S
MAGNETIC Declination is the
angle between the direction on
the compass and True South (or
North.
Compass needles is affected by
magnetic core of the Earth.
*GPS devices preconfigured!
*Change every few years,
slightly.
West Coast:
+15º
180º - (15º) = 165º
East Coast:
-15º
180º - (-15º) = 195º

West Coast-
western declination:
+15º
180º - (15º) = 165º
Compass tell you S is W of what it
really is.
East Coast-
eastern declination:
-15º
180º - (-15º) = 195º
Compass tell you S is E of what it
really is.

Mounting methods and locations:
● Consider latitude
● Consider tilt
● Consider shading
But also:
Electrical service, system integration,
placement of components
Options:
roof mount, ground mount, pole mount

What is their vision and ultimate desire?
● What is their motivation (selling points)
● Determine energy usage and
expected/desired offset (size/$)
● Do they want a roof or a ground mount
system?
● What are their preferences visually?
Customer Assessment:

Energy usage and offset
Energy Audit:
http://youtu.be/YolBP0-vkBU
Recommend reductions in use ( highest value
for customer / of system)
Consider adding EA to your skills set as an
installer/team or partnering with an AE
company (value to installer)

Location and Visuals:
Will primarily depend on availability of
shade-free area, but specific preferences
could play into decision.
● Shading
● Roof condition
● Safety and code
● Costs (and rebates)
● Architectural appearance, aesthetics and
color

Indiegogo Campaign:
Online Solar School Development
http://www.indiegogo.com/projects/online-
solar-school-development?c=home
http://www.indiegogo.com/projects/online-
solar-school-development?c=gallery

Sarah Raymer
sraymer@solpowerpeople.com
Director of Education and Training
Services
SolPowerPeople, Inc.
NABCEP Certified PV
Installation Professional
Certificate #042013-107

053013 pv system site assessment (1)